75 lines
1.5 KiB
Plaintext
75 lines
1.5 KiB
Plaintext
[#lit]
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[section lit]
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[h1 Synopsis]
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template <class C>
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struct lit;
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This is a [link parser parser].
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[table Arguments
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[[Name] [Type]]
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[[`C`] [[link boxed_value boxed] character value]]
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]
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[h1 Description]
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Parser accepting only the `C` character. The result of parsing is the accepted
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character.
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[h1 Header]
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#include <boost/metaparse/lit.hpp>
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[h1 Expression semantics]
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For any `c` boxed character the following are equivalent:
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lit<c>
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accept_when<
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one_char,
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boost::mpl::lambda<boost::mpl::equal_to<boost::mpl::_1, c>>::type,
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error::literal_expected<c::type::value>
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>
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[h1 Example]
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#include <boost/metaparse/lit.hpp>
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#include <boost/metaparse/start.hpp>
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#include <boost/metaparse/string.hpp>
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#include <boost/metaparse/is_error.hpp>
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#include <boost/metaparse/get_result.hpp>
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#include <type_traits>
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using namespace boost::metaparse;
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static_assert(
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is_error<
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lit<std::integral_constant<char, 'x'>>
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::apply<BOOST_METAPARSE_STRING("a"), start>
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>::type::value,
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"a different character should be an error"
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);
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static_assert(
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is_error<
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lit<std::integral_constant<char, 'x'>>
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::apply<BOOST_METAPARSE_STRING(""), start>
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>::type::value,
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"empty input should be an error"
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);
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static_assert(
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get_result<
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lit<std::integral_constant<char, 'x'>>
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::apply<BOOST_METAPARSE_STRING("x"), start>
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>::type::value == 'x',
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"result of parsing should be the accepted character"
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);
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[endsect]
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